The woman dubbed the ''Black Widow'' has filed an appeal against her conviction for murdering her husband.

A Christchurch High Court jury last year found 50-year-old Helen Milner guilty of poisoning her husband, Philip James Nisbet, at their Halswell home in May 2009.

Milner was also found guilty of attempting to murder Nisbet in a similar way about a month earlier.

She was sentenced last month to a minimum of 17 years in jail - one of New Zealand's toughest terms for a female killer.

A Court of Appeal registry officer today confirmed Milner had filed an appeal against her conviction.

He was unable to provide any further details about the application.

Nisbet's sister, Lee-Anne Cartier, said she was not surprised Milner was trying to appeal, but said the move was ''frustrating''.

''Someone really needs to find something for that woman to do in jail that doesn't involve using taxpayer money.''

She was worried about her parents finding out, causing them more stress.

''It's just another thing we've got to get over and it's just not fair on victims that we have to keep dealing with this.

''Everyone needs to get on with their lives; they don't need to deal with anymore of her bull***t. Phil's kids, her kids, they all have a right to a future without her dragging them through more of this.''